Sounding signal adjustment



Dec. 31, 1940. .1. WHITE EIAL SOUNDING SIGNAL ADJUSTMENT Filed Jan. 21, 1957 22 llllllflllll l B L-pie,"

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fl 1 /08 I Raga/7 fisriscbejn I! Patented Dec. 31, 1940 UNITED STATES PATENT OFFICE SOUNDING SIGNAL ADJUSTMENT Delaware Application January 21, 1937, Serial No. 121,468

' 3 Claims.

This invention relates to sounding signals and is particularly directed to adjusting means for the same.

It is an object of this invention to provide an adjusting means for a sounding signal whereby the frequency may be altered from the fundamental.

Another object of this invention is to provide frequency altering means for a sounding signal 1 that will be within the control of the operator.

Another object of the invention is to provide a frequency control for sounding signals whereby each unit of a pair of horns may be satisfactorily adjusted so as to result in either a beat note or a is blended note when the signal devices are sounded in unison.

A still further object is to provide means whereby the frequency of a horn power plant can be adjusted to the absolute resonant pitch of the 47 air column.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred embodiment of the present invention is clearly shown.

In the drawing:

Fig. 1 is'a sectional view of a sounding signal device illustrating one modification of the instant invention, the motor cap orhousing having been removed.

Fig. 2 is a fragmentary view in plan with parts shown in section, it being a view substantially as indicated by the line and arrows 2-2 of Fig. 1. 35 Fig. 3 is a fragmentary view, partly in elevation and partly in section, substantially as indicated by the line and arrows 3-3 of Fig. 2.

Fig. 4 is a sectional view similar to Fig, 1, but

illustrating a modification of the frequency ad- 40 justing means, the view being that indicated by the line and arrows 4-4 of Fig. 5.

Fig. 5 is a sectional view of the same substantially as indicated by the line and arrows 5-5 of Fig. 4.

45 Fig. 6 is a sectional view similar to Fig. 1, illustrating a further modification of the frequency altering means.

Fig. 7 is a fragmentary transverse sectional view with parts shown in elevation, substantially as indicated by the line and arrows 1-! of Fig. 6.

Fig. 8 is a view in elevation withparts broken Fig. 10 is a horizontal section on line Ill-40 of Figure 9.

Where sounding signal devices are used in pairs for the purpose of producing a resultant note, of either blended or a beat note type, the individual 5 frequencies of operation of the separate devices contribute much to producing a pleasing and eflicient warning signal. There need be but slight variation from the prescribed frequency of either unit to cause a dissonance of sound when the units 10 are sounded in pairs. Even when exercising extreme care in manufacture, the devices, when completely assembled, will produce tones of slightly different pitch, as respects successive horns coming from the same production line. It has, therefore, heretofore been necessary to try these horns out in pairs, in order to obtain the desired result, as to smoothness of tone and blending effect. It has been discovered that these same horns may have their fundamental frequency altered by appropriate means, so that they can be regulated to pair off with practically any other unit of the same production line, thereby providing the desired note relation. While it has been found that there are numerous means and mechanisms that can be adopted for altering the fundamental frequency, it has also been found that the most satisfactory results can be obtained by use of means or mechanism pressing upon the oscillatable assembly of the signal device. 80

The foregoing objects have been accomplished by providing a yieldable member that presses upon the oscillatable assembly, such as the diaphragm, and preferably at or near the center thereof, or at that point where it is usually connected to the operating armature. Means are then provided for supporting the yieldable memher and for varying its spring pressure upon the oscillatable assembly.

With particular reference to the drawing, and to the modification illustrated in Figs. 1, 2 and 3,

a support ID is provided that comprises a collar member l2 with a cap I4, which taken together are hollowed out to form an air passage l6 leading to a trumpet (not shown) the inner end of the passage i 6 opening into a chamber 20. The support also includes a motor bridge 22 engaging a ring 24 that are clamped to the collar member I2 by screw devices 26, all as is the usual custom and well known to those experienced in the art. Where desirable, the bridge 22 may be so fashioned as to be clamped directly to the member It! with the elimination of the ring 24.

A diaphragm 28 extends over the chamber 20 and is carried by the support, it being clamped end of the stud '36 being connected with the armature 38, and with the contact actuating mechanism in any suitable manner such as indicated at 48 and 50 respectively. A circuit breaker mechanism 52 cooperating with the device 58 is supported by a yoke 54 that is in turn fixed to the motor bridge 22 in any convenient and desired manner. An armature spring 55, has one end fixed to the yoke and the other end secured, to

the armature rod 36 adjacent the armature 38.

The frequency adjusting means disclosed in Figs. 1, 2 and 3, comprises a blade spring 60, the free end 62 of which is adapted to bear upon the center of the diaphragm assembly, as for instance the projecting washer 42. The remote end of this spring is bifurcated at 64 to provide a pair of parallelly extending legs 66 and 68 through which rivets 10 pass and are turned over to fasten the spring to a bracket member 12, substantially as illustrated in Figs. 2 and 3. The bracket member comprises a piece of angle iron, one flange of which is attached to the spring 60 by the rivets l0, and has an intermediate extruded portion 14 threaded to receive a screw device 16 that passes through a plain hole 18 in the motor bridge 22.

The other flange of the bracket 12 is cut-away somewhat so as to leave a tongue 80 projecting through a slot 82 in the motor bridge, on which tongue it receives a take-up device in the nature of a bowed spring 84, apertured to pass over the tongue 80, where it is held in flexed relation by means of a pin 86 passing through a hole in the end of the tongue 80. The free ends of the spring 84 engage the upper surface of the motor bridge and thereby draw the bracket member 12 against the underside of the bridge, such that the shoulders 88 left in forming the tongue 88 form a fulcrum engagement against the underside of the bridge member, substantially as indicated in Fig. 3. This construction is such that the pressure applied to the spring for loading the oscillatable,

' the spring tension of the dished diaphragm 28 and the armature supporting spring are in a state of equilibrium. When the oscillatable assembly is actuated due to the periodic energization of the magnet 32 the diaphragm will'be rapidly oscillated toward and from the collar member at a definite frequency, there resulting an audible signal emanating from the trumpet I8, whether thesound product be the result of audible vibrations set up within the diaphragm, or whether the sound product be the result purely of the vibrating air column incident to the oscillatable movemerit-"of thediaphragm.

This tone product, purely for the convenience of reference, is called the basic frequency where it is the result of the operating device unattended by any modifying means such as the frequency altering means. However, this basic frequency may not be the best for efficiency, or may not meet the requirements of the producer, especially when he wishes to pair the horn off with another. It is this conditionthat gives rise to the need for some altering means by which the frequency of I the motor and oscillatable assembly can be adjusted to absolute resonant pitch of the air column.

The frequency altering means hereinbefore described, and specifically illustrated in Figs. 1 to 3 inclusive, when applied to the structure as illustrated disturbs the equilibrium of the oscillatable assembly andmoves it ever so slightly to one side of its quiet position. In so doing the spring 60, adjustably supported at one end from the motor bridge 22,has one end thereof bearing upon the center of the diaphragm assembly as indicated at 62. Operation of the mechanism under these conditions will result in a sound signal emanating from the trumpet [8 that is of a different pitch than that of the basic frequency, or that sound product produced by the operation of the device uninfiuenced by the frequency adjuster. As the frequency adjusting means are altered by means of the screw stud 16 to alter the force with which the spring presses upon the oscillatable assembly, the frequency of vibration of the diaphragm will be changed, which will result in changing the pitch of the sound product emanating from the trumpet I8.

In the frequency adjusting means thus far described, adjustment of the screw 16 causes the bracket 12 to rock upon the motor bridge 22 along the fulcrum provided by the shoulders 88 and the underside of the motor bridge. When the screw I6 is run in, the bracket 12, as viewed in Fig. 1, will be rocked on its fulcrum in a counterclockwise direction which increases the spring pressure upon the center of the diaphragm assembly. When the spring 16 is rotated in the opposite direction, so as to allow the bracket to rotate in a clockwise direction, the spring pressure upon the diaphragm assembly will be less, this resulting in a lowering of the frequency from that which may have theretofore obtained.

Generally the same facts obtain as respects the other modifications. In the modification illustrated in Figs. 4 and 5, the adjustable spring tension is applied to the diaphragm at places 28a, intermediate the pointof attachment to the armature stud 36, and the point of support around the periphery of the diaphragm. Specifically, the spring means comprises a bowed member 90, the free ends 92 of which bear upon the diaphragm, and the central bight 94 of which is provided with a saddle or clip 96 extruded at 98 to provide a seat to engage the sharpened end of a screw stud [00, the stud being threaded through the motor bridge 22 at I02, and held in adjusted relation by a clamp nut I04. When the screw stud N10 is run in toward the spring 98 the spring pressure upon the diaphragm 28 is increased, which as described above raises the pitch of the ultimate sound product. Here, too, the force applied to the spring for increasing the pressure on the oscillatable assembly is distributed by means of the saddle 96 that extends across the spring. a

In the modification illustrated in Figs. 6 and 7, a spring blade 16 is secured to the motor bridge 22 by rivets I08 and has its-free end pressing upon the center of the diaphragm assembly as indicated at III]. Spacers I 09 may be inserted between the fixed end of the spring I06 and the bridge 22 if it is so desired. An adjusting screw II2 passing through a bowed spring I I4 constituting a take-up device and pressure member, is threaded through the motor bridge 22 at I IS. The spring II4 has an end portion I I8 that engages a pad I20 lying over the spring, after the portion II8 extends downward between the magnet frame 30 and the bridge 22. The spring portion I I8 has a square end I 22 that contacts the end of the pad I2!) and thus increases the area of pressure upon the spring I06. Adjustment of the screw IIZ varies the flexing of the spring IE6 and thereby regulates the force of the spring pressing upon the diaphragm assembly. The underside of the screw head and the spring II4 have provisions to restrain relative rotation by accident and constitutes alocking means that tends to hold the screw H2 in the adjusted position. These provisions are generally indicated at I23 in Fig. 9. The looking means consists of the lugs H3 on the underside of the head of screw II2, which engage in slots I I I cut in the spring I I 4 around the opening for screw I I2.

In the modification illustrated in Fig. 8, the collar member 22' is joined to the trumpet I8 by means of an elbow 22a, on which is provided a threaded boss :24 subtantially centrally disposed over the center of the diaphragm assembly. A threaded stud I25, threaded within the boss I24 and fitted with a lock nut I26, provides an adjustable abutment I21 to seat a helical spring I28 whose opposite end embraces the end of the threaded stud 36 and thereby exerts adjustable spring pressure upon the center of the diaphragm assembly. In this particular instance the diaphragm actuating mechanism is enclosed by the usual cover I 30.

We claim:

1. In a sounding signal device wherein a magnet motor is supported by a base plate, and includes a circuit breaker yieldably engaging an oscillataible assembly, and operates to oscillate the assembly for setting an air colimin into vibration,- the combination with said base plate, cf means other than the circuit breaker for altering the frequency of assembly oscillation, which frequency altering means comprises a flexible member anchored to the base plate, a strut engaging the flexible member remote from its anchorage, and a screw device carried by the base plate for adjustably forcing the strut into engagement with the flexible member, whereby the flexible member may be flexed to exert spring pressure upon the diaphragm assembly.

2. In a sounding signal device wherein a magnet motor is supported by a base plate, and includes a circuit breaker yieldably engaging an oscillatable assembly, and operates to oscillate the assembly for setting an air column into vibration, the combination with said base plate, of means other than the circuit breaker for altering the frequency of assembly oscillation, which frequency altering means comprises a flexible member anchored to the base plate, a strut engaging the flexible member remote from its anchorage, and a screw device carried by the base plate for adjustably forcing the strut into engagement with the flexible member, whereby the flexible member may be flexed to exert spring pressure upon the diaphragm assembly, said strut comprising a bowed spring having a right angle extension contacting a pressure pad over the flexible member and a resilient arm formed to engage the base plate.

3. In a sounding signal device wherein a magnet motcr is supported by a base plate, and includes a circuit breaker yieldably engaging an osc llatable assembly, and operates to oscillate the assembly for setting an air column into vibration, the combination with said base plate, of means other than circuit breaker for altering the fre quency of assembly oscillation, said means comprising a leaf spring independent of the circuit breaker, secured at an end to the base plate, and having a normally free end forcibly engaging the central region of the oscillatable assembly, a pressure member mounted on the opposite side of said base plate, and having a portion extending through the plate to forcibly engage the spring, and means for regulating the force with which the pressure member engages the spring, said pressure member having a yieldable portion adapted to be flexed by said means.

JOE WHITE. RALPH BERTSCHE, JR. 

